How about this: "A Localizer Back Course"
is just like a regular Localizer Approach except that Left is
Right, and Right is Left. In addition, it may, or may not, have
a Glide Slope. If it has a Glide Slope, it is called a "Localizer
Back Course with Glide Slope".

Hmm, I think I liked the "confusion definition"
better.

"Humor" aside,
what is a Localizer Back Course?

In a conventional Localizer, the signal radiates
outwards from the end of the runway, along the extended center
line of the runway. Usually, a by-product of this is a signal
that radiates in the reverse direction. Some installations take
advantage of this "spurious signal" and use it for an
instrument approach.

Wait a minute. Tell me
again what a "Localizer Approach" is

A Localizer Aproach is a regular ILS without
the Glide Slope. Because there is no "up/down" information
given a Localizer Approach is referred to as a "non-precision
approach". However, just to muck up the waters, there are
Back Course approaches that include a Glide Slope. They're kind
of rare, but they're out there.

If you are not clear on this, please read the
tutorial "Localizer
Approaches" in the Tutorial Section.

OK, but what's with this
"Left is Right and Right is Left" business when you
talk about the "Back Course"?

When you fly a "conventional" Localizer
Approach, or any approach for that matter, a needle deflection
to the left means that your desired course is to the left, and
that you as the pilot must correct the plane's heading to the
left to recapture the approach course. The opposite applies for
right deflection of course.

However, in a Localizer Back Course, if the
needle deflects to the left it means that your desired course
is to the right, and that you must correct in the opposite direction
to recapture the desired approach course. In other words, left
is right and right is left.

Perhaps they should have named it the "Localizer
Backwards Approach".

Huh?

Let's take a look at a Localizer Approach.

Picture the Localizer signal also "propagating"
in the opposite direction, back down the runway.

Notice the "barbed" section on the
Localizer Front Course? That's the "right side" of the
Localizer. The "clear" section is the "left side"
of the Localizer. When you are in the "barbed side",
your course indicator (HSI, VOR head) will be on the left side
of the instrument, indicating that the desired course is to the
left. The opposite, naturally, applies to the left side of the
Localizer Course.

In "the old days", VOR instrument
displays had painted markings. The Right side of the display had
a blue arc, while the Left side had a yellow arc, representing
the Right and Left sides of the Localizer.

You
may come across these displays in older aircraft.

Now, notice on the drawing above that shows
the Front and Back portions of the Localizer that the "barbed"
side and the "solid" side of the Localizer are both
on the right side, as viewed from Localizer Front Course end of
the runway. The "clear" side is on the left side. Hold
this thought, it's important for what's to follow.

Let's show some indicators
in various locations on the Localizer Approach using an HSI

Here is how your HSI display will look at various
points on the Localizer Front Course, runway 23.

Position 1:Position
2: Position
3:

And here's how the old fashioned VOR head would
look:

Position 1:
Position 2:
Position 3:

In all cases, the CDI (Course Deviation Indicator)
indicates where your desired course is, and which way you have
to go to get back on course.

Now, let's see what the HSI display looks
like over on the Back Course side.

Position 4:
Position 5:
Position 6:

And here's how the old fashioned VOR head would
look:

Position 4:
Position 5:
Position 6:

Whoa, that's confusing. So, on the Back Coure,
Left is Right, and Right is Left.

Why is this so?

Because the displays, HSI and VOR head, don't
care which way the "pointed end of the airplane" is
facing. They could be placed in a flying saucer, it doesn't matter.

And, as far as the VOR head is concerned, it
doesn't matter what you have the CDI set to. If you were in position
"6" (or any other position), in the above example, you
could twirl that knob all around the "dial". The indication
would not change.

Here's where the "old timers" with
their old VOR head display, the one shown above with the "yellow
and blue sectors", had an "edge". Notice that in
all of the displays showing the VOR head, that the needle is always
showing which side of the Localizer the instrument is in? No matter
if you are on the Front Course, or the Back Course, the needle
is in the correct "zone". An old joke was that these
pilots wore a pair of colored gloves when flying Back Course Approaches.
They put a blue one on the right hand, and a yellow one on the
left. If the VOR head display showed the needle to the left, in
the "blue zone", they could look at the blue glove on
their right hand and know that they had to go to the right to
get back on course. True? I don't know, but it's a good story.

Well, my airplane doesn't
have those cute little blue and yellow "zones" on the
VOR head

No, it doesn't. So, if you're flying a Back
Course Approach with a VOR head only, just remember that left
is right and vice versa.

And now, drum roll please,
the secret to end this confusion

When flying a Back Course, simply turn the
HSI Course Selector to the Front Course heading.

What? It's that simple?

Yep, that's all there is to it. Let's look
at the approach diagram again, this time turning the Course Selector
on the HSI to the Front Course heading, 230 degrees.

Position 4:
Position 5:
Position 6:

Now the indications are correct. Left is
left, and right is right.

Wait a minute, you couldn't
do this with the VOR head, how come you can do it with the HSI?

Because of the way the HSI is made. ((Remember
that with the standard VOR head the entire "card" turns.)
When you rotate the Course Selector knob on an HSI, the one down
there on the lower left corner, the center part
of the HSI rotates. When that happens, the CDI needle always stays
on the "correct" side. Why did they design it that way?
So that you could make a Back Course Approach without "opposite
indications". Well, there are some other navigation display
benefits too.

OK, now that you know the "secrets"
of the Back Course, let's fly an approach.

NOTE: It assumed that the you have read the
tutorial on ILS Approaches.
We will not cover the approach in great detail, only those things
that are distinctive to the Back Course.

Here is a Back Course Approach into the old
Denver Stapelton Airport:

There
it is in plain English. This is a Back Course Approach. And, it
has DME. Because there is no Glide Slope, there has to be a way
for you, the pilot, to know where you are on the approach. In
could be radials from a VOR, in this case it's DME fixes.

Ah,
there it is. The information that you need to set your HSI. See
that "FRONT CRS 351"? The reason that it is there is
so you can set your HSI to the Front Course heading so that you
will get "correct" Left / Right indications during the
approach.

There
probably is a "remnant" of the Glide Slope for the ILS
runway 35 approach drifting around in the airspace.

Here
is the step-down profile. Notice that the first DME fix is referenced
off of the Denver VOR, and that all of the following ones are
from the Localizer. Also, notice that Maltese Cross at the NDB?
That indicates that this is the Final Approach Fix, where you
start your Final Approach Segment of the approach.

When flying this approach you would tune your
ADF to Thornton, 281Kc. This will aid in orientation, and give
you a display of your passage over Thornton.

Approach Control would have you at 9,500 feet
when you are established on the 15 mile arc off of the Denver
VORTAC. Once you intercept the Localizer, and are established
on it, you would step down to 9,000 feet. At the 13.0 DME fix
you would descend out of 9,000 for 7,000. At Thornton, or the
5.7 mile DME fix, you would descend out of 7,000 for the MDA,
Minimum Descent Altitude, of 5,580 feet. The Missed Approach Point
is at .8 DME.

And all this time, Left would be Left, and
Right would be Right.

Localizer Back Course Approaches? Hey, piece
of cake!

This ends the tutorial on Localizer Back Courses.
If you have any suggestions, corrections, or comments, please
contact me.
Thank you.

This narrative, along with aditional
content, is available as a CD or an eBook.